“Last night was a victory for [Romney], but the problem that the conservatives have is that they don’t have a candidate that they’re settled on,”said David R. Gergen, the director of the Harvard Kennedy School’s Center for Public Leadership and a political analyst.

Though a record number of Iowans turned out at the caucuses, no standout emerged among the pack of Republicans vying to take on President Barack Obama in the general election. Romney and Santorum each garnered roughly 25 percent of the vote. Congressman Ron Paul trailed closely behind with roughly 21 percent, while former House Speaker Newt Gingrich and Texas Governor Rick Perry failed to rally voters as they had expected, ending with roughly 10 percent of the vote each.

Government professor Theda R. Skocpol said that a fundamental shift has taken place within the Republican Party which helps explain Romney’s difficulty in winning over a majority of party voters. Skocpol said that the rise of the Tea Party movement, separate from the party’s mainstream, has hurt Romney because Tea Party voters are dissatisfied with his reputation as an establishment politician.

Yet that growing movement has not helped any another candidate enough to lift their choice above Romney in the polls. “I do think the problem that Tea Partiers have is that they can’t unite behind a single candidate,” Skocpol said. “There is a split between evangelical and libertarian wings of the party.” She pointed out that Santorum and Paul, both affiliated with the Tea Party, split the faction’s votes but received almost 50 percent of caucus-goers' votes between them.

In a speech in Iowa on Tuesday night, Romney, a Harvard Law School and Business School alumnus, declared that day’s caucuses a victory for his campaign.

Prior to Tuesday’s results, many questioned whether the former Massachusetts governor, often derided as a “moderate” by other candidates, could win over Iowa conservatives. Professors say that eking out a win by a single-digit margin was not a feat that indicates that Romney pulled off an impressive victory.

“The turnout last night was not what they had hoped,” said Gergen. “If you look at the percentage that Romney actually won, it’s the lowest percentage by which any person has won in the history of the Iowa caucuses. He’s got an enthusiasm gap .. that he’s got to fix.”

Romney’s numbers in Iowa fell slightly from four years ago, when he also campaigned for the presidential nomination. That year, he lost the state to former Arkansas Governor Mike Huckabee. But while candidates such as Santorum, Gingrich, and Paul campaigned hard in the state for months, Romney did not to enter the fray until December, at which point he increased the money and the time he spent in Iowa.

“Romney actually went all in in Iowa in the last month, and the fact that he wasn’t able to improve his standing from four years ago means he’s in for a longer battle, and that’s not what he wanted,” Skocpol said.

Even among traditional Republicans, Romney has stirred up little enthusiasm. Professors said that voters see him as difficult to relate to, yet he has held on to the frontrunner position in a hotly contested race because they also see him as more likely to win in the general election than other candidates.

“He is clearly by all the polls seen as more electable that anyone else on the Republic side, and he is closer ideologically to where most of the country is,” Gergen said.

The results in Iowa, which come close to a three-way tie, reflect a general dissatisfaction with the candidates with which Republican voters have been presented so far, professors said.

“[Romney’s] inability to break through 25 percent in national polling is the search for an alternative,” said government professor Stephen D. Ansolabehere, a scholar of democracy and elections.

Congresswoman Michele Bachmann dropped out of the running after receiving very little support from Iowans. Gingrich and Perry chose to remain in the race despite the setback they experienced in Iowa.

“I think the narrative about the selection is going to be sharpened where we’re now seeing this as a choice between true conservatism and electability,” Ansolabehere said of the race for the nomination in the weeks ahead.

Analysts have widely predicted that Romney will easily win in New Hampshire’s primary next Tuesday, but questions about his chances in southern states’ primaries later this month remain. Those questions, Harvard professors said, may prolong the competition during the primary season far longer than Republican leaders might hope.

—Staff writer Nicholas P. Fandos can be reached at nicholasfandos@college.harvard.edu.